Continuing to face this problem since Necrom and none of the official support guides help whatsoever.
First login attempt
Error 334
Second login attempt
Error 103
Third login attempt
Error 307
Attempting to login again after that just results in Error 307. Sometimes waiting 20 minutes allows me to login, and sometimes not. Completely unpredictable and has to be server-side considering I've tried every official fix suggested for each of the errors I listed. Have tried deleting addons, repairing the launcher, restarting my PC, opening ports for my router, etc. It's all serverside.